The effects of peak strain, one of the most important parameters of a hypoelastic constitutive model along with peak stress, on the behavior of plane concrete are evaluated in this paper. The modified biaxial strength envelope of Kupfer and Gerstle is used for the peak stress equations. For the numerical analysis of plane concrete, a nonlinear finite element algorithm developed is used. The incremental orthotropic stress-strain model which is easy to use in connection with nonlinear finite element analysis is employed as a constitutive model. Comparisons between numerical results with different sets of peak strain equations and test results are made. Based on the observation and comparison of the stress-strain responses of numerical and experimental results, the peak strain equations are proposed.

This paper presents the earthquake response analysis results on the Large-Scale Seismic Test (LSST) structure which was built at Hualien in Taiwan. The seismic analysis is carried out using a computer code KIESSI, which has been developed based on the three-dimensional axisymmetric finite element method incorporating infinite elements for the far field soil region. The soil and structural properties obtained from the pest-correlation study of the forced vibration tests (FVT) as well as the unified model that was made from the insitu tests for soil and experiments for concrete specimens, is utilized to predict seismic responses. The ground accelerations recorded at a site 56.5m from the test structure are used as control motions. In general, the predicted responses using the FVT-correlated model show better agreements with the measured responses than those using the unified model. However, the damping appears to be underestimated for the rocking motion in the present analysis model. Comparisons of transfer functions between analysis results and measured data show that the nonlinearity in the soil medium near the structure can be significant in spite of the small magnitude of the earthquake excitation.

In the present study, the criteria has been established as an alternative to the test beam procedure in order to carry out the structural integrity evaluation for CANDU type nuclear power plant, using the experimental data obtained from the embedded strain gages during the pre-operation proof pressure test for the containment building, including the theoretical analysis of variations of material properties and time-dependent phenomena of the prestressing system. In the criteria proposed, variations of measurement were estimated based on the previous reports because of lacking of experimental data, thus leaving uncertainties in the prediction of the upper and lower bounds of the strain. Further study including the validation of variation sources and quantification will enhance the evaluation criteria with a higher confidence.

In recent years, precast prestressed concrete segmental box girder bridges have been increasingly constructed. Expansion diaphragm segment of this type bridge transfers forces from the superstructure onto bearing or column, and plays an important roll of anchorage zone for longitudinal prestress forces. Non-linear stresses occur inside of diaphragms by these extensive concentrated forces. Strut-and-tie model is a rational method to design for these complex regions in which stress field is disturbed and is verified by many tests. In this study, the strut-and-tie models are proposed to design an expansion segment rationally. A formula to determine the effective transverse prestress forces is proposed on the basis of these models. The present study is expected to provide an effective tool to design expansion segment of prestressed oncrete bridges rationally.

This paper is presented to obtain the dynamic responses of steel plate girder bridges in consideration of road surface roughness using 3-D vehicle model. The bridge and vehicle are modeled as 3-D bridge and vehicle model. respectively. The road surface roughness of the roadway and bridge decks are generated from power spectral density (PSD) for different road surface roughness. The vehicles are modeled as two nonliner vehicle model with 7-D.O.F. for dump truck and 12-D.O.F. for tractor-trailer. Bridge-vehicle interaction equations are derived and impact factor of the steel plate girder bridges for different parameters are presented. The simply supported steel plate girder bridges from "The Standard Design Examples of The Highway Bridges Superstructure" published by the Ministry of Construction in Korea are used. The spans of the bridges we 20.0m, 30.0m and 40.0m and their widths are 11.0m, respectively. The impact factors of the bridges are calculated for 15t dump truck and 53T/C 40T/L tractor- trailer, with different speed and road surface roughness.

This paper presents an efficient numerical method whose stability is proved for computation of eigenpair derivatives. The method is very simple and a compact algorithm and gives an exact solution. Furthermore, the proposed method can save the computational time and computer memory. The eigenpair derivatives can be obtained by solving algebraic equations with side conditions in the both case of nonrepeated and repeated eigenvalues. As an example to demonstrate the efficiency of the proposed method in the case of distinct eigenvalues, a cantilever plate is considered, and a cantilever beam in the case of repeated eigenvalues. Especially, the proposed method can save the computer memory about 33% and the computational time about 30% in the case of repeated eigenvalues. The design parameter of the cantilever plate is its thickness, and that of the cantilever beam its height. It is important to note that the numerical stability of the proposed algorithm is proved.

The fatigue of concrete is of great importance in the design of bridges, railroads, pavements, and offshore structures, and so on. In these structures, the load is applied repeatedly for a very large number of cycles. Therefore, the fatigue of concrete is very important. It was reported that stress ratio, the rest time of load, and load sequence had an effect on the fatigue of concrete, that strength of concrete, the size of concrete section, and load frequency hardly had an effect on the fatigue of concrete. In this study, it will be showed how much initial crack depth has an effect on the fatigue of concrete. The experiments of both static test and fatigue test were conducted. In the static test, the concrete beam specimens of size are tested in three-point loading condition. The experiment of static test was undertaken to investigate the notch sensitivity and fracture toughness of concrete. The investigation indicates that the concrete beams with notch length up to 5.0 cm are little notch sensitive, but with notch length of 7.5 cm are a little notch sensitive. In the fatigue test, results indicate that initial crack depth has influence on the fatigue of concrete. We measured strains on four-point bending load beams for fatigue test. The strain development consists of three different stages : A rapid increases from 0 to about 10% of total fatigue life. A uniform increases from 10 to about 80% Then, a rapid increases until failure, if failure takes place. The secant modulus of elasticity is reduced during the fatigue life. It seems that the higher the stress level is, the larger the decrease is.

The use of an envelope function to augment multiple buckling loads is discussed in this paper. The characteristics of the Kreisselmeier-Steinhauser function is introduced and its smoothing effect is demonstrated by using a simple example. A procedure is given in which a discontinuous constraint function is converted to a smooth one and it is applied to the optimal design of a ring stiffened shell. The minimum weight design is obtained for a given external hydrostatic pressure and it is found to be a bimodal design. Different values of the envelope function parameter are tested and the results indicate that by choosing an appropriate parameter, the optimal design is obtained and computational efficiency can be improved at the same time.

The main purpose of a structural monitoring system is on finding my function abnormalities of the corresponding structures, which usually indicate structural damage, based on the sensor signals. A key challange of to the eventual deployment of this system is the need for reliable but noise-tolerant autonomous on-line signal processing of the generated sensor signals . This paper focuses on this signal processing aspects needed in structural health monotoring system and explores artificial neural networks for their potential usefulness in processing sensor signals for the purposes of detecting the existence and location of crack damage of instrumented structures.

Due to the increasing traffic volumes, heavy loaded trucks and use of high strength materials, fatigue problems are reported as main causes of structural failures of steel highway bridges. However, the fatigue design procedure in current practice is so crude to consider the variety of traffic patterns, such as vehicle types, weights, etc. In this study, for the purpose of development of rational fatigue damage estimation method, the impact coefficient model has been proposed. The traffic flow models are also developed, which can be applied to any traffic patterns. The sensitivity analysis on cumulative fatigue damage has been performed to evaluate the effect of important parameters, such as average daily truck traffic volume (ADTT), average daily traffic volume (ADT), characteristic of consecutive vehicle type, impact coefficient, etc.